The present invention relates generally to structures for mechanically and electrically interconnecting circuit boards using a circuit component. More particularly the present invention relates to magnetic circuit components such as a transformer having a bobbin structure adapted for electrically and mechanically interconnecting two or more circuit boards in a substantially side-by-side configuration.
Magnetic circuit components such as transformers and inductors are commonly used in a variety of electrical applications, including power supplies. Generally, a magnetic circuit component may include an electrically conductive winding positioned around a core made of a magnetically permeable material. Typically, a core is made of a ferrite. The conductive winding is positioned on a bobbin structure shaped for receiving the core. Additional conductive windings may be placed around the same core or bobbin structure. A second core may also be positioned near the conductive winding to form a closed-loop magnetic flux path around the bobbin structure. Each coil, or winding, may include one or more turns. The electrical characteristics of the component generally depend on the number of turns of each conductive winding and the relative placement of each winding around the core or cores.
Conventional magnetic circuit components are generally configured for surface mounting onto a circuit board using terminal connection pins extending from the component body. The connection pins are placed into holes on the surface of a circuit board and are soldered to electrical connection locations on the circuit board, thereby mechanically attaching the component to the circuit board while electrically connecting the component to the circuit. Typically, parts of the electric circuit to which a magnetic component is connected are printed directly onto a circuit board substrate, forming a printed circuit board.
A printed circuit board may be formed in several layers, each layer including a unique pattern of conductive material, known as a multi-layer printed circuit board. One common printed circuit board configuration includes a circuit pattern printed only on one side of a flat, two-sided circuit board, generally referred to as a single-sided printed circuit board. Another conventional printed circuit board configuration includes circuit patterns printed directly onto both sides of a circuit board substrate, typically known as a double-sided printed circuit board. Multi-layer and double-sided printed circuit boards require more expensive design, layout and fabrication processes than single-sided printed circuit boards, and it is thus desirable in the art to use single-sided printed circuit boards wherever possible to reduce cost. Many electronic applications and circuit components require the use of a multi-layer or double-sided circuit board either for optimal functionality or for obtaining a desired electronic device profile.
The prior art generally teaches the use of a single contiguous double-sided circuit board for an entire circuit in applications where any individual region of a circuit requires a double-sided circuit board. However, it is often desirable to separate one double-sided circuit board into multiple smaller single-sided circuit boards oriented in a side-by-side configuration to reduce costs. A multiple circuit board configuration, however, requires both electrical interconnection among boards and mechanical support between boards. Others have attempted to electrically interconnect adjacent single-sided, double-sided and multi-layer circuit boards in a single circuit using electrical and mechanical connectors between boards. Various types of electrical and mechanical connectors are known for such connection, including sockets, pins, cables, horizontal standoffs and spacers. However, these connector components add additional size, cost and complexity to electric circuits and electronic devices. Prior art connectors also add additional modes of device failure by increasing both the number of individual electrical connections that may become disconnected and the number of mechanical connections that may become dislocated. Also, another design goal in many electronic devices having both high-voltage and low-voltage circuit regions is to provide magnetic isolation between the high-voltage and low-voltage regions. Prior art electrical and mechanical circuit board connectors generally do not provide magnetic isolation between high-voltage and low-voltage circuit regions.
Typically, in an electrical device such as a power supply, a circuit board is surrounded by an enclosure to prevent circuit components from being exposed to the environment. During use, magnetic circuit components generate heat locally inside the enclosure. Heat must be dissipated from the component to ensure proper functionality and to prevent circuit damage, component failure, or fire. One mode of heat dissipation from a surface-mounted magnetic circuit component includes heat conduction through a thermal linkage between the magnetic component and the enclosure wall, whereby the enclosure serves as a heat sink. Prior art surface-mount magnetic component configurations, however, limit the ability of a magnetic circuit component to be thermally coupled to an enclosure wall because prior art surface-mount configurations generally place a circuit board between the magnetic component and the enclosure wall. Conventional circuit board placement blocks direct thermal contact between the magnetic component and the enclosure wall. Moreover, the close proximity of the circuit board to the surface-mounted magnetic component in the prior art allows heat conduction by the circuit board, potentially causing damage to nearby circuit components.
Others have attempted to solve the problems associated with surface-mounted magnetic component heat dissipation by positioning the magnetic component farther away from the surface of the printed circuit board, using a series of mechanical standoffs to provide an air gap between the component and the circuit board. Because a magnetic component is often the tallest component in a circuit, such prior art raised surface-mount configurations generally increase the maximum height of the circuit extending above the surface of the circuit board, necessitating the use of a larger enclosure. Generally, it is desirable to produce electronic devices having smaller device profiles and increased volumetric power density. In contrast, the prior art approach causes an undesirable increase in the overall size of the electrical device and reduces volumetric power density. Others have also attempted to address the problem of surface-mounted magnetic component heat transfer by adding heat removal structures, such as heat sinks and fins to surface-mounted magnetic components. These structures, however, also take up additional space within the electronic device enclosure, thereby increasing electronic device profile and reducing power density.
Accordingly, there is a need in the art for providing a magnetic circuit board connector component for mechanically and electrically connecting circuit boards. The magnetic circuit board connector component must eliminate unnecessary circuit board material, improve heat dissipation from the magnetic component, provide structural support to a circuit board, allow single-sided circuit boards to be used with double-sided printed circuit boards in one circuit, provide magnetic isolation between high-voltage and low-voltage circuit regions, and reduce device profile while increasing power density. Also desired is a circuit board assembly having two or more circuit boards mechanically and electrically interconnected by a magnetic component.